1. Field of the Invention
The present invention is in the field of window structures and is directed more particularly to a simple economical window which is highly resistant to the ingress of moisture, dirt or drafts, has a high degree of protection against heat loss, and presents, at the same time, a narrow sight line.
2. The Prior Art
Numerous attempts have been made to construct window assemblies including operating sash components which, without undue complexity, provide a high degree of isolation of the interior from the exterior in the closed condition of the window.
In the typical window construction, a first seal is effected between the window frame and the frame of the operating sash. A second seal is defined between the glass lites or panels themselves and the operating sash, it being apparent that leakage of either of such seals will compromise the integrity of the barrier defined by the window construction.
In order to optimize the barrier effectiveness defined by the window, various weather-stripping arrangements between the frame and the operating sash have been proposed. To prevent leakage between the glass panels or lites and the operating sash, a multiplicity of glazing systems have been suggested.
In window devices of the type described, particularly those which are double glazed to minimize heat loss through the window panels, it has been proposed, where the frame material is made of metal, to form both the operating sash and the fixed frame of two discrete metal frames linked or connected by thermal insulating material, such windows being known as "thermal break" windows. The interposition of the insulating material which eliminates metal-to-metal contact between the frames interrupts the heat path from the interior to the exterior, reducing heat loss. Thermal break windows give rise to additional problems, however, in that stock material from which frames are made are relatively expensive to manufacture, and by virtue of the interposed plastic between the stock material components, lacks the rigidity of a unitary metal frame. The resultant loss of rigidity prevents the frame, and particularly the operating sash, from structurally reinforcing the glass lites against flexture where, by virtue of relative movement between the lites and the operating sash, the glazed connection is compromised, with attendant undesirable effects.
Thermal break windows, as well as virtually all other windows, by reason of the necessity for providing two laterally displaced seal areas about the perimeter (the division line between the fixed and the operating sash on the one hand, and the glazed connection between the glass lites and the operating sash on the other) present an aesthetically undesirable appearance, resulting from the presence of multiple breaks of the seal lines. Moveover, since the glazing or gasketting whereby the outer glass pane is mounted in its frame is, in conventional windows, exposed directly to the elements, the glazing tends, in time, to harden and crack, with resultant leaks and other structural defects.